The present invention relates to cyclic peptide compounds also referred to as macrocyclic polypeptides. In particular, the present invention relates to cyclic peptides containing alanine moieties. The invention further relates to a process for making the novel cyclic peptides of the invention.
Numerous cyclic peptide compounds are known or have been described in the art. Previously however, the synthetic methods employed have been tedious and complicated requiring the use of expensive reactants and suffering from low yields of the desired cyclic peptide product.
Examples of known cyclic peptides include L-Pro.sup.1 -tentoxin disclosed by D. Rich et al., J.A.C.S., 100, 2212 (1978). The compound was prepared by standard blocking and deblocking techniques followed by intramolecular cyclization in pyridine solvent.
It is also known to cyclo oligomerize N-alkyl aziridines with various cationic initiators such as BF.sub.3 or paratoluene sulfonic acid to give tetraazacyclodecanes; see, e.g., S. Tsuboyama et al., Tet. Lett., 16, 1367-1370 (1970); G. R. Hansen et al. J. Heterocyclic Chem., 5, 305 (1968).
In U.S. Pat. No. 3,305,493, linear polymers of an acrylic acid ester and a polyalkylenepolyamine are disclosed. The linear polymers were formed by heating a Michael addition product of the acrylic acid ester and the polyalkylenepolyamine to a temperature of from about 90.degree. C. to about 130.degree. C. A similar process is disclosed by U.S. Pat. No. 3,445,441.